The invention relates to a substrate, such as a metallic thin film or plate, having catalyst compositions on the surfaces of each opposite side of the substrate and methods for applying the catalyst compositions to the opposite sides of the substrate. The invention further relates to catalyst surfaced substrates having predetermined shapes formed for use in micro component reactors.
Disclosures of processes for the deposition of ceria particles on a substrate include U.S. Pat. No. 5,063,193 to Bedford et al. which describes a wash coat of high surface area ceria particles and the preparation thereof in which cerium carbonate is converted to ceria via chemical reactions and calcination; U.S. Pat. No. 6,051,528 to Brezny which describes a wash coat created by dissolving cerium carbonate to form cerium acetate which is then treated by spray pyrolysis to form a ceria powder; and U.S. Pat. No. 5,989,648 to Phillips which describes the plasma generation of supported metal catalysts. U.S. Pat. No. 5,453,641 describes V-shaped or tapered micro-channel substrate surfaces and U.S. Pat. No. 5,002,123 also describes V-shaped micro-channels tapered in the direction of flow of fluid through the channel. U.S. Pat. No. 4,777,560 shows a heat sink formed of an integral element of thermally conductive material.
The surfacing of opposite sides of a metallic thin film or plate with a catalyst composition presents numerous difficulties. Disadvantages associated with teachings of the patents referenced above are encountered in the production of micro-channel reactors and heat exchange devices. For example, when a substrate surface is coated with a catalyst by means of thermal gas spraying and the molten coating on the metallic film is cooled by means of vacuum contact with a V-shaped heat sink, providing a coating on the opposite side of a substrate already having one coated surface is not possible with the prior art because of the need for contact with a heat sink. To coat an opposite side of an already coated substrate by thermal spraying is problematic because re-heating occurring during the coating of side two would cause the surface of coated side one of the substrate to melt and puddle, degrading the surface and decreasing the efficiency of the catalyst coating.
The present invention provides a bi-laterally surfaced (or coated) substrate. A first predetermined surface, such as a catalyst, is first applied to a side of the substrate by a thermal spray; a second predetermined surface, such as the same or a different catalyst, is then applied to the opposite side of the substrate by a physical vapor deposition process, such as electron beam evaporation or a sputtering process. Neither surface is substantially degraded during the bi-lateral surface coating process. After both sides of the substrate are surfaced, the substrate may be physically manipulated or formed into a desired shape without affecting the surface properties of the opposite sides. The invention is particularly useful in the deposition of catalyst materials on surfaces of components used in micro-component reaction chamber assemblies.